XL) SOME INVESTIGATION ABOUT DRAWING AND HEAT-TREATING CONDITIONS By using undrawn filaments which were spun by the wet spinning system of dimethyl formamide-glycerine and were dried at room temperature, the effects of draw ratio and drawing temperature on the mechanical properties of drawn filaments and the maximum draw ratio at variouss temperatures were investigated. The effects of various heat-treating conditions at fixed and relaxed state on the mechanical properties of heat-treated

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... ts were also investigated by using drawn filaments obtained by the continuous spinning and drawing process. (XLI) EFFECT OF HEAT TREATMENT CONDITIONS ON FIBER PROPERTIES To make clear the mechanism of heat-treatment of drawn filaments obtained by wet spinning process, the drawn filaments which were obtained by the wet spinning of polyacrylonitrile solution in dimethyl formamide into butanol bath were heat-treated under various heat-treating conditions and the effects of these heat-treating conditions on the properties of heat-treated filaments were investigated. As the drawn filaments obtained by the wet spinning into butanol bath have remarkably dense texture, their fine textures or structures scarcely changed by heat-treatment, and it was, therefore, impossible to find the changes of fine textures by almost observation with an optical microscope, but by observation of ultra-thin sections with an electron-microscope, it was possible to detect the existence of many fine voids in the cold-drawn filaments which are not heat-treated yet, and the disappearance of these voids by heat-treatment. Heat-treated samples are stable and show little shrinkage in the next heat-treatment whose heattreating temperature was lower tnan the preceding heat-treating temperature, Samples heat-treated by steaming were much more stable than those dry-heat-treated Knot strength became smaller by heat-treatment under fixed state, while elongation and knot strength became larger by heattreatment under relaxed state. The effect of heat-treatment by steaming under relaxed state on the mechanical properties was more remarkable than that of heat-treatment by dry-heating under the same state.